Midstroke locking devices



March 14, 1961 R. A. cHAcE MrnsTRoxE LOCKING DEVICES Filed Maron s, 1959 INVENTOR. ,ww/WD A. eff/A05 BY W @LM/u L6/Mam A frog/V616 United Sete, een@ s `z9, 14,63f` i M IDSTRQKE LOGKING DEVICES- Richard.. A. Chaco, Bellevneg Wash., `assignor, by mesne assignmentsrtowestern Hxdraulic;&.Sei-viee- Company, f he Gardena, Caliisaeeuw.rathmnfv California EiledMar- 3:, 1.95%*Sen No. 796,833

.81 Claims.y (Cl. 121-40) This. iniienten eoncems a two-nari hydraulically unlocked.; actuator, o1; thesaine can. b e used merely as a retaioinggdevicmj whereby-a.. member` secured; to wone part ts form st rould-i,besimplerY and thelocking terebluiof hetype disclosed in` the `patd r rtefnakigetNo: 2,764,132,

ial Seed-Qual, view of Lthedevice, withi i butshew-.iethe rengiefef disdene. ,.a.ey1inder10 1wthin. whichV a Pis- .,ly insldins; the; .pie-ten.. 2.1 and; e pis-ton rod ipneeeble. VTthemision. `red .-20. .preieefs through QthefheuSirns'l-s wherebythe housing may be @hanane-@Q be, held- .against movement .ontofbepermitted or; cansegirtompye assthecase maybe; andi-the opposite end, th pistonir. d2Y rsiconnected-I to the other such t .u athis embedm-.lentfeenneetionsare provided atl, -angat ltnfor4 admissionof iluidatVV superior pres- Surete main-@Irretheepnesite endsof. thefcyIi-nder 10 and eleaseoflesserE pressllm at the; other. end, such flu jressureserving;torinsureretention of parts inthe unl`oc1k-etiposition? asswellpas, moving or assisting; in the einentfrelatively.- of thevr twomembersl Y .hefleglsing device/.beine hefnistenl andi pistonv rod l 'i nludeslockingdog-means ,e guided. at. .21 ingthe .assembly for radi-al Aprop These.,locking` AclogswhenV in istr-yY withftheggroov; 1.4 Lwithirifthe interior of he ho ingYJ1,-.will..engage oppositelydirectedrshoulders .141; tofretain thk able` and Ain. ai.fniidstrokeY ,or centered" position us pjectto l the; housing; 1f; andgcylinderlfl: 4It will be that the. sliotrldersiv 14a; and 1'4-b5. ini accordance vyil he` principles, .0.f the. :.two patents fmentioned above', fwit-s;:l .V.tJ.$2i;;= and :thie-,suriaces.A at:v the; tips offthel locking dogs 3 which engagewith".I -thesnsholders '-arecomple-f mentally beveled.

. The locking1 device furtheri'ncludes togglemeans such i as 4the links 4:,pivotally mounted .atj540j upon a slidev or plungenlS, which is guided within a..bore 22 withinythe the assembly 'of which part,whereby, ithin tstborefto centeredtorfmidstroke position.. andr ed.; reassure-movements.. Normally, the prbiee radiallnoutwerdlvt..but thisy is e assembly, including the VPiston Patented Mar. 14, 1961 swing .inwardly into a. position. permitting. inward or fretractive.movementoffthe dogs; 3. Upon movement of thev plunger to.thee n'ght', thetoggle. links. 4 will swing outwardly. into alignment; with the dogs to move them into and retain themin their locking position, provided they. are. in registry with the groove 14. A shoulder 30 upon the dogs will engage the toggle links 4 to prevent appreciable movement of the latter beyond their aligned locking position.

A spring Sreactsbetween the piston 2 and the plunger Soto urge the plunger. and hence thetoggle links and dogs 3 in the sense to lock them. It is this spring which, in the absence of pressure, within the cylinder, eiects relooking.

The plunger 5- isformedat one end, as indicated at 51,

asa smal'kpiston. reciprocable within the bore 22 under theinuenceof. hydraulic pressure admitted from the left end of the cylinder 10 to the right hand end of the piston 51, by way of a port 23V i'n the piston and piston rod: assembly. In addition, the opposite end of the plunger at the` rightfisjexposedto pressure within the righthandenduof thecylinder 10., which is the opposite .4 side, o-fpthepistonzfto Vthatwhich subjects the piston 51 to'gpressure; Pressureapplied atA either ,place tends to Urge the, plunger to the .1eft1i11` opposition to its spring 50 tovenable retraction ofthe lock-ing dogs. Upon removal of` pressureyitherspring 50 acts to urge the dogs 3 into locking`engagement with.` the shoulders, butthis movementfcari actuallyj ccjur; onlywhen' the piston 2 is in its.` midstrokejposition. 1

it. is desirable; however,v tol permit the piston. when unlockedgtomove.freely and :repeatedly to either side ofei'ts` midstrokae; or ,locked position. Accordingly, detent means suchasVt-hespringfpressedA balls 6 are provided andere carried-inthe piston andpiston rod assembly in positionto engagefin recesses 31 of the dogs in order to retain the dogsiretracted.V Thispositionof the parts is` shown.V in Figure .2. The force of spring 50 is sucient torelease thezdetents. 6.5. provided there is no hydraulic pressure inetherend of the cylinder to urge the plunger, 51in the unlockingj direction.

Assuming that the parts are in the locked position of Figure. 1, applicationgof pressure uid through t-he connection 12e-.will rst cause pressure to be applied to the. right` hand face 51a of the piston 51, urgingA it to the Yleft since itsA left hand face` communicates at all times withY a lowpressure region.

jected to this pressure atvits` leftrhand face, which cany .The pistoni. 2 is Aalso subeiect movementfbetweenrthe members connecte-dito the piston rod and theV cylinder, respectively, but .actual move: ment ,can lbe accomplished. by separate actuatorsfor such members if preferred. Thepvmovemepnt-of the piston 51VV to the; leftretracts :the toggle links 4, andthe reaction be-Vv tween the beveledltipsof the dogs and the shoulders 14a under the. urging; of the. piston 2; to the rightsmoves ther dogsrinwardly, vand eiects movementof lthe-piston and piston rod assemblyto the right. J If it were desired; to move to the left, application oi pressure iluid through the connection at lflxwould-` first act on the projectingright.

end of the 'plunger 55; moving it to the left and, at'the same time, the pressurer acting,A upon the piston 2 would` tend tojmove the latter to-the left, but again, actual movement .can be causedby separatev actuators.

Retractive movement `of. .theldogsI 3 brings their die-..1

pressionszl31-into AVengavgenletltwith. the de tents and .theselatterpaidedf by ,pressuregim one. end or the 'other ofthe cyliiiden `1 retain.` the. dogs retracted,` permitting movement of the pistonandpistonfrod assembly repeatedlypast theniidstrokeposition without reengagingthe Olli'.

to one another throughout the range of movement indicated by the full line and dot-dash line positions of Figure 2. p

Whenever locking is required, regardless of the positions of the parts, the control surface is centered by its normal control means, which centers the piston 2, and then pressures are relieved from the opposite faces of the piston 2. This allows the plunger 5 to move to the right under the inuence of spring 50. The force of the spring 50 is sucient to overcome the restraining eiect of the detents 6 and, upon the dogs 3 coming into registry with the groove 14, the spring 50 will snap them outwardly into locking position and retain them thus locked until pressure is again applied to one or the other face of the piston 2.

This invention in certain respects is similar in subject matter to that disclosed in a companion application, Serial No. 796,943, tiled the same day as this application, and claims generic to the common subject matter are included in the latter case.

I claim as my invention:

1. A midstroke locking device comprising a cylinder ported at its opposite ends for admission of pressure iiuid to either end, and relief at the opposite end, an assembly including a piston axially slidable within said cylinder under the influence of pressure applied to one or the other of its faces, and a piston rod projecting from one end of the cylinder, said assembly having a through axial bore communicating at its opposite ends with the respective ends of the cylinder, a plunger received in and closing said bore, and movable axially therein in a first sense under the influence of pressure within a rst end of the cylinder, spring means to return said plunger, upon relief of such pressure, in the opposite, second sense, passage means atfording communication between the second end of the cylinder and a vface of the plunger to move the latter 4also in the irst sense, in opposition to said spring means, under the inuence of pressure within the second end of the cylinder, and complemental fixed and movable locking elements carried by the cylinder and by the piston assembly, respectively, and disengageable by pressure-induced movement of the plunger, but interengageable when brought into registry by the axial movement of the piston to a midstroke position, said spring means and plunger being operatively connected to the movable Vpiston-carried locking element to urge the latter into locking position only in the absence of pressure applied to the plunger from either end of the cylinder.

Y'2. A device of the character set forth in claim 1, including detent means engageable between the assembly and the movable locking means Vand arranged to retain said-locking means in released position so long as pressure isapplied `from either end of the cylinder to the plunger, but of a strength to be overcome and disengaged by said spring means upon cessation of such pressure.

` 3. AV device of the character setl forth in claim 1, wherein the-movable locking means includes dog means guided in the assembly for radial projeetive and retractive movement, toggle devices mounted upon and swingable relative yto the plunger, and operatively engaged with but disconnected from said dog means to urge the latter in the prjective direction under the influence of the spring means,l but leaving the toggle devices free of the dog means for retractive'movemennand the complemental fixed locking means on the cylinder comprises a shoulder engageable by the dog means when projected.

A device ofthe character'set lforth in claim 3, including two oppositely facing shoulders spaced apart for simultaneous engagement by the dog means when parts are in the midstroke'locking position. Y

Y 5, A` device of the character set forth in claim 4, wherein the shoulders Vare beveled, and the shoulder-engaging tips ofthe Vdog means are correspondingly beveled, for retractive movement of the dog means independently of .but upon retractive-movement of the toggle devices, under Y the influence of pressure applied to the plunger at either end thereof, and axial shifting of the assembly under the same pressure, in either direction.

6. A midstroke locking device comprising a cylinder arranged for connectionv toa'tirst member and ported at its oppositeends for admission of pressure iluid to either end and relief from the opposite end, a piston slidable axially within said cylinder, and itself axially bored, a piston rod projecting from said piston through one end of the cylinder for connection to a second member movable relative to the rst member, a plunger tting within the pistons bore for axial movement therein, and exposed to cylinder pressure at the end distant from the piston rod, a spring operatively connected to said plunger to urge it away from the piston rod, in opposition to pressure at its exposed end, a port in the piston admitting tluid pressure from the piston rod end of the cylinder into the pistons Ibore, at the side of the plunger to shift the latter in opposition to its spring, dogs mounted in the piston and guided for radial projective and retractive movements, shoulders within the cylinder wall, intermediate its ends, engageable by said dogs and located to lock the piston in a midstroke position against axial movement in either direction, toggle links pivotally mounted upon the plunger for swinging outwardly, and operatively connected to the dogs to project the latter into locking position when so swung outwardly, to secure the two members against relative movement, or to free the dogs for retractive movement when the toggle links are swung inwardly, and a detent carried by the piston and engageable with the dogs whenfin retracted position, to retain them unlocked while the piston moves with relation to the shoulder to either side of its locked position.

7. A securing device as set forth in claim 6, wherein the shoulders are beveled, and the shoulder-engaging tips of the dogs are complementally beveled, to effect retraction of t-he dogs when the toggle links are swung inwardly,

' and pressure is applied at either side of the piston.

8. A midstroke locking device comprising a main cylinder arranged for connection to a first member and ported at its opposite ends for admission of pressure uid to either end and relief from the opposite end, a main piston slidable axially within said main cylinder, and itself axially bored, a piston rod projecting from said main piston through one end of the cylinder for connection to a second member movable relative to the first member, a plunger iitting within the main pistons bore for axial movement, and subject to pressure in the cylinder end distant from the rod, a supplemental piston carried by said plunger at the rod end of the main piston, the main piston having a supplemental cylinder wherein said supplemental piston is axially reciprocable, with its rod end Y exposed to low pressure, passage means affording communcation between the opposite end of the supplemental cylinder and the rod end of the main cylinder, vfor movement of the supplemental piston and plunger towards the rod end of the main piston when subjected to pressure at either end of the main cylinder, spring means to return the plunger and supplemental piston to'Y an initial position in the absence of pressure at either end of the main cylinder, and complemental xed and movable locking elements carried by the cylinder and by the main piston, respectively, for interengagement when brought into registry by the axial movement of the piston, said spring means and plunger being operatively connected to the movable piston-carried locking element to urge the latter into locking position only in the absence of pressure applied to the main piston from either end of the main cylinder.

References Cited in the tile of this patent UNITED STATES PATENTS 

